Resin composition and method for producing the resin composition

Abstract

To provide a resin composition that yields resin molded articles with good biodegradability and heat resistance at 25°C. [Solution] A resin composition comprising a biodegradable resin and a cellulose structure mainly composed of a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.7.

Description

Technical Field

[0001] The present invention relates to a resin composition and a method for producing the resin composition.

Background Art

[0002] Patent Document 1 proposes "a resin composition comprising a polylactic acid-based or aliphatic polyester-based resin and a nucleating agent, wherein the nucleating agent is composed of a crystalline polysaccharide".

[0003] Patent Document 2 proposes "a degradable resin composition containing 75% by weight or more of polylactic acid, and containing 0.05 to 10% by weight of cellulose nanofibers with respect to polylactic acid".

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem of the present invention is to provide a resin composition capable of obtaining a resin molded body having good biodegradability and heat resistance at 25°C as compared with the case where the degree of substitution of the cellulose derivative is less than 0.2 or 1.7 or more in a resin composition containing a biodegradable resin and a cellulose structure mainly composed of a cellulose derivative.

Means for Solving the Problems

[0006] The means for solving the above problems include the following aspects. <1> A biodegradable resin, and A cellulose structure containing, as a main component, a cellulose derivative having a substitution degree of 0.2 or more and less than 1.7, and A resin composition containing <2> The resin composition according to <1>, wherein the cellulose structure is present in the biodegradable resin with an average diameter of 0.001 μm or more and 50 μm or less. <3> The resin composition according to <1> or <2>, wherein the number average molecular weight of the cellulose derivative is 15,000 or more and 50,000 or less. <4> The resin composition according to any one of <1> to <3>, wherein the heat of crystallization of the resin composition is 32 J / g or more and 45 J / g or less. <5> The resin composition according to any one of <1> to <4>, wherein the biodegradable resin is at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate. <6> A method for producing a resin composition, comprising mixing a biodegradable resin and a cellulose structure containing, as a main component, a cellulose derivative having a substitution degree of 0.2 or more and less than 1.7. <7> The BET specific surface area of the cellulose structure is 0.1 m 2 / g or more and 100 m 2 / g or less. The method for producing the resin composition according to <6>. <8> The method for producing the resin composition according to <6> or <7>, wherein the number average molecular weight of the cellulose derivative is 15,000 or more and 50,000 or less. <9> The method for producing the resin composition according to any one of <6> to <8>, wherein the heat of crystallization of the resin composition is 32 J / g or more and 45 J / g or less. <10> The biodegradable resin is at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate. <6> ~ <9> A method for producing the resin composition described in any one of the following. [Effects of the Invention]

[0007] <1> or <5> According to the invention, a resin composition is provided that includes a biodegradable resin and a cellulose structure mainly composed of a cellulose derivative, and that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the degree of substitution of the cellulose derivative is less than 0.2 or 1.7 or more. <2> According to the invention, a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the average diameter of the cellulose structures present in the biodegradable resin is less than 0.001 μm or greater than 50 μm. <3> According to the invention, a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the number average molecular weight of the cellulose derivative is less than 15,000 or more than 50,000. <4> According to the invention, a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the crystallization heat of the resin composition is less than 32 J / g or more than 45 J / g. <6> or <10> According to the invention, a method for producing a resin composition is provided, which includes mixing a biodegradable resin with a cellulose structure mainly composed of a cellulose derivative, and which yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the degree of substitution of the cellulose derivative is less than 0.2 or 1.7 or more. <7> According to the invention, the BET specific surface area of ​​the cellulose structure is 0.1 m². 2 Less than / g or 100m 2 A method for producing a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the value exceeds / g. <8> According to the invention, a method for producing a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the number average molecular weight of the cellulose derivative is less than 15,000 or more than 50,000. <9> According to the invention, a method for producing a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the crystallization heat of the resin composition is less than 32 J / g or more than 45 J / g. [Modes for carrying out the invention]

[0008] The following describes an example embodiment of the present invention. These descriptions and examples are illustrative and do not limit the scope of the invention. In numerical ranges described stepwise within this specification, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described stepwise. In numerical ranges described within this specification, the upper or lower limit of that numerical range may be replaced by the values ​​shown in the examples.

[0009] Each component may contain multiple types of the relevant substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0010] [Resin composition] The resin composition according to this embodiment comprises a biodegradable resin and a cellulose structure mainly composed of a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.7. Hereinafter, the resin composition according to this embodiment will also be referred to as "this composition." Furthermore, a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.7 will also be referred to as "specific cellulose derivative." Furthermore, a cellulose structure containing the specific cellulose derivative as a main component will also be referred to as "specific cellulose structure." This composition, with the above configuration, yields a resin molded article with good biodegradability and heat resistance at 25°C. Hereinafter, biodegradability at 25°C will also be referred to as "low-temperature biodegradability".

[0011] In recent years, environmental awareness, exemplified by the SDGs (Sustainable Development Goals), has led to a shift in the perception of the importance of living. Interest in biodegradable resins is growing. In particular, among biodegradable resins, polylactic acid (PLA) is a highly biodegradable resin that is carbon neutral. For this reason, PLA is expected to be a substitute for petroleum-derived plastics. Biodegradation of biodegradable resins typically occurs in compost at a temperature of 55°C. However, in recent years, there has been interest in biodegrading resin molded products in ordinary households. Therefore, there is a need for resin molded products that possess both heat resistance and high biodegradability in compost at 25°C, i.e., low-temperature biodegradability.

[0012] Therefore, in this embodiment, a specific cellulose structure is present in the biodegradable resin. That is, a cellulose structure mainly containing a cellulose derivative with a substitution degree of 0.2 or more and less than 1.7 is used. As a result, a resin molded article with good low-temperature biodegradability and heat resistance can be obtained. The reason for this is presumed to be as follows.

[0013] In resin molded products containing cellulose structures within biodegradable resin, the biodegradation of the cellulose structures occurs first in compost. As the cellulose structures biodegrade, the surface area of ​​the biodegradable resin increases. This increase in surface area makes the biodegradable resin more readily available to come into contact with decomposing enzymes and microorganisms in the compost. In particular, resin molded articles containing specific cellulose structures within biodegradable resins exhibit high biodegradability even at low temperatures in compost. Specifically, when the degree of substitution of the specific cellulose derivative is below the aforementioned upper limit, the biodegradability of the cellulose structure itself is increased. Therefore, biodegradation of the cellulose structure is more likely to occur first even in compost at a temperature of 25 degrees Celsius. As a result, it is presumed that the low-temperature biodegradability of the resin molded product will be increased. Furthermore, when the degree of substitution of the specific cellulose derivative is above the aforementioned lower limit, a large amount of acidic components derived from the substituent are generated during the biodegradation of the cellulose structure. When the biodegradable resin comes into contact with these generated acidic components, biodegradation of the biodegradable resin becomes more likely even in compost at a temperature of 25 degrees Celsius. As a result, it is presumed that the low-temperature biodegradability of the resin molded product will be enhanced.

[0014] In addition, the cellulose structures present in the biodegradable resin are presumed to function as crystal nucleating agents within the resin. In other words, the cellulose structures promote the crystallization of the biodegradable resin. This is thought to improve the heat resistance of the molded resin product. In particular, it is believed that the heat resistance of resin molded products can be further improved by incorporating specific cellulose structures within biodegradable resins. Specifically, when the degree of substitution of the specific cellulose derivative is below the aforementioned upper limit, the compatibility between the cellulose structure and the biodegradable resin is reduced. As a result, the function of the cellulose derivative as a crystal nucleating agent in the cellulose structure is more easily exhibited. This is expected to further improve the heat resistance of the resin molded product. Furthermore, when the degree of substitution of the specific cellulose derivative is above the aforementioned lower limit, the dispersibility of the cellulose structure in the resin improves, making it easier for it to function as a crystal nucleating agent. As a result, it is presumed that the heat resistance of the resin molded product will be further improved.

[0015] For the reasons stated above, it is presumed that this composition will yield a resin molded article with good low-temperature biodegradability and heat resistance.

[0016] The details of this composition will be described below.

[0017] <Biodegradable resin> Biodegradable resins are resins that are broken down into water and carbon dioxide by microorganisms. In this embodiment, a biodegradable resin means a resin that undergoes aerobic biodegradation under a method in accordance with ISO 14855-1:2012, with a biodegradation rate of 5% or more in 28 days.

[0018] Examples of biodegradable resins include polyester resins, natural polymers, and polyvinyl alcohol.

[0019] Examples of polyester resins include aliphatic polyester resins and aliphatic aromatic polyester resins. Examples of aliphatic polyester resins include polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxyalkanoates (PHA), polycaprolactone, polyalkylene succinates, and polyhydroxyalkanoates such as polyalkylene succinates / adipates. Examples of polyhydroxyalkanoates (PHA) include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH). Examples of polyalkylene succinates include polyethylene succinate (PBA) and polybutylene succinate (PBS). Examples of polyalkylene succinates / adipates include polyethylene succinate / adipate and polybutylene succinate / adipate (PBSA). Examples of aliphatic aromatic polyester resins include polybutylene adipate / terephthalate copolymer resin (PBAT) and polytetramethylene adipate / terephthalate copolymer resin.

[0020] Examples of natural polymers include starch, cellulose, chitin, chitosan, gluten, gelatin, zein, soy protein, collagen, and keratin.

[0021] Examples of biodegradable resins include cellulose derivatives (cellulose acylates, cellulose ethers, hydroxyalkylcellulose, and carboxymethylcellulose). Examples of cellulose acylates include cellulose acetate (cellulose monoacetate, cellulose diacetate (DAC), cellulose triacetate), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).

[0022] Among these biodegradable resins, from the viewpoint of environmental suitability, at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate is preferred as the biodegradable resin, and in particular, resins that fall under both biomass resin and biodegradable resin (especially polylactic acid) are preferred.

[0023] These biodegradable resins may be used individually or in combination of two or more types.

[0024] The biodegradable resin content is preferably 50% by mass or more and 99.9% by mass or less relative to the resin composition, and more preferably 90% by mass or more and 99.9% by mass or less.

[0025] <Cellulose structure> The cellulose structure contained in this composition mainly comprises a specific cellulose derivative. In other words, the cellulose structure mainly comprises a cellulose derivative with a degree of substitution of 0.2 or more and less than 1.7. "Mainly composed of a specific cellulose derivative" means that the total content of the specific cellulose derivative relative to the cellulose structure is 90% by mass or more. Preferably, the total content of the specific cellulose derivative relative to the cellulose structure is 95% by mass or more, more preferably 98% by mass or more, and even more preferably 100% by mass.

[0026] (Specific cellulose derivatives) The specified cellulose derivative is not particularly limited as long as it is a cellulose derivative with a degree of substitution of 0.2 or more and less than 1.7. Cellulose is a polymer compound in which numerous β-glucose molecules are polymerized in a linear chain by glycosidic bonds. Cellulose derivatives are compounds in which different substituents are introduced to the hydroxyl groups contained in cellulose molecules.

[0027] Examples of cellulose derivatives include cellulose esters and cellulose ethers. Examples of cellulose esters include, in addition to cellulose acylates described below, cellulose aromatic organic acid esters such as cellulose phthalate and cellulose benzoate; cellulose inorganic acid esters such as cellulose nitrate, cellulose sulfate, and cellulose phosphate; cellulose organic acid·inorganic acid mixed esters such as cellulose nitrate acetate; and the like. Examples of cellulose ethers include carboxyalkyl cellulose, hydroxyalkyl cellulose, alkyl cellulose, and the like. The cellulose structure may contain only one of these cellulose derivatives, or may contain two or more thereof.

[0028] From the viewpoint of generating a large amount of acid components and the like with the biodegradation of the cellulose structure, the cellulose derivative preferably contains at least one selected from the group consisting of cellulose esters and carboxyalkyl cellulose, more preferably contains cellulose esters, and even more preferably contains cellulose acylate. Hereinafter, cellulose acylate will be described as an example of the cellulose derivative.

[0029] Cellulose acylate is a cellulose derivative in which at least a part of the hydroxy groups in cellulose is substituted (acylated) with an acyl group. The acyl group is a group having the structure of -CO-R AC (R AC represents a hydrogen atom or a hydrocarbon group.).

[0030] Cellulose acylate is, for example, a cellulose derivative represented by the following general formula (CA).

[0031]

Chemical formula

[0032] In the general formula (CA), A 1 , A 2 and A 3Each of the A's independently represents a hydrogen atom or an acyl group, and n represents an integer of 2 or more. 1 n A 2 and n A 3 At least some of these represent acyl groups. There are n A in the molecule. 1 These may be all identical, partially identical, or different from each other. Similarly, n A in a molecule 2 and n A 3 Each of these can be entirely identical, partially identical, or different from one another.

[0033] A 1 , A 2 and A 3 The acyl group represented by may have a hydrocarbon group in the acyl group that is linear, branched, or cyclic. 1 , A 2 and A 3 The acyl group represented by the symbol preferably has a linear or branched hydrocarbon group, and more preferably a linear one.

[0034] A 1 , A 2 and A 3 The acyl group represented by may have a hydrocarbon group that is either saturated or unsaturated. 1 , A 2 and A 3 The acyl group represented by is preferably a saturated hydrocarbon group.

[0035] A 1 , A 2 and A 3 The acyl group represented by is preferably an acyl group having 1 to 6 carbon atoms. In other words, as cellulose acylate, a cellulose acylate in which the acyl group has 1 to 6 carbon atoms is preferred.

[0036] A 1 , A 2 and A 3The acyl group represented by may also be a group in which the hydrogen atom in the acyl group is replaced by a halogen atom (for example, a fluorine atom, a bromine atom, or an iodine atom), an oxygen atom, a nitrogen atom, etc. 1 , A 2 and A 3 It is preferable that the acyl group represented by is unsubstituted.

[0037] A 1 , A 2 and A 3 Examples of acyl groups represented by include formyl group, acetyl group, propionyl group, butyryl group (butanoyl group), propenoyl group, and hexanoyl group. Among these, acyl groups having 2 to 4 carbon atoms are more preferred from the viewpoint of improving the biodegradation rate of the cellulose structure, and acyl groups having 2 or 3 carbon atoms are even more preferred.

[0038] Examples of cellulose acylates include cellulose acetate (cellulose monoacetate, cellulose diacetate (DAC), cellulose triacetate), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB).

[0039] From the viewpoint of high biodegradability, cellulose acetate is preferred over cellulose acylate.

[0040] The degree of substitution of the cellulose derivative is 0.2 or more and less than 1.7, and from the viewpoint of low-temperature biodegradability and heat resistance, it is preferably 0.7 or more and 1.5 or less, and more preferably 1.1 or more and 1.3 or less. The degree of substitution of a cellulose derivative is an indicator of the extent to which the hydroxyl groups of cellulose are substituted by substituents. In other words, if the cellulose derivative is, for example, a cellulose acylate, the degree of substitution is an indicator of the degree of acylation of the cellulose acylate. Specifically, the degree of substitution of a cellulose acylate means the average number of substitutions in which the three hydroxyl groups in the D-glucopyranose unit of the cellulose acylate are replaced by acyl groups. The above average number of substitutions is the average value obtained by averaging the number of substitutions for the D-glucopyranose units of all cellulose acylate molecules contained in the cellulose structure. For example, even if there are molecules with an intramolecular average number of substitutions of less than 0.2 or 1.7 or more, a cellulose acylate whose average number of substitutions for all molecules is between 0.2 and 1.7 is considered a specific cellulose derivative.

[0041] The degree of substitution of cellulose acylate is, 1 The hydrogen is determined by the integral ratio of the peaks derived from cellulose and hydrogen derived from the acyl group using 1H-NMR (JMN-ECA / JEOL RESONANCE). The degree of substitution of cellulose acylate is measured using a sample obtained, for example, as described below. Specifically, a sample is obtained by dissolving a cellulose structure in a solvent such as dimethyl sulfoxide. When measuring cellulose structures in a resin composition, the cellulose structures may be extracted from the resin composition by the following method. Specifically, the resin composition is polished, and the cellulose structures are separated by specific gravity separation of the polishing powder. The degree of substitution of cellulose derivatives other than cellulose acylate can be determined using the same method as for cellulose acylate. The method for controlling the degree of substitution of a cellulose derivative is selected according to the type of substituent. For example, if the cellulose derivative is a cellulose acylate, the degree of substitution may be controlled by saponifying the cellulose acylate with an alkali, which has a higher degree of substitution. In other words, a specific cellulose derivative can be obtained, for example, by performing a degree of substitution adjustment operation such as saponification on a commercially available cellulose derivative. Hereinafter, the cellulose derivative before performing a degree of substitution adjustment operation such as saponification will also be referred to as the "original cellulose derivative." The degree of substitution of the original cellulose derivative can be, for example, 1.7 or higher.

[0042] The number-average molecular weight of the specific cellulose derivative is preferably 15,000 to 50,000, more preferably 20,000 to 40,000, and even more preferably 25,000 to 35,000. If the number-average molecular weight of a specific cellulose derivative is above the lower limit mentioned above, the compatibility between the specific cellulose structure and the biodegradable resin decreases. As a result, the function of the specific cellulose structure as a crystal nucleating agent is more easily exerted. When the number-average molecular weight of a specific cellulose derivative is below the above upper limit, the low-temperature biodegradability of the specific cellulose structure increases.

[0043] The number-average molecular weight of cellulose derivatives is measured using gel permeation chromatography (differential refractometer Optilab T-rEX / Wyatt Technology, multi-angle light scattering detector DAWN HELEOS II / Wyatt Technology, column TSKgel α-M and α-3000, one of each / Tosoh Corporation) with dimethylacetamide (with 0.1M lithium chloride added) as the solvent. The number-average molecular weight of cellulose derivatives is measured using a sample obtained, for example, as described below. Specifically, a sample is obtained by dissolving a cellulose structure in a solvent such as chloroform. When measuring a cellulose structure in a resin composition, the cellulose structure may be extracted from the resin composition using the method described above.

[0044] (Other ingredients) The specific cellulose structure according to this embodiment may contain other components besides the specific cellulose derivative.

[0045] (Characteristics of specific cellulose structures) -Porous structure- The cellulose structure may be a porous structure or a non-porous structure. Applying a porous cellulose structure increases the contact area with biodegradable resins, making it easier to improve low-temperature biodegradability. Furthermore, it facilitates the function of a crystal nucleating agent, leading to improved heat resistance.

[0046] -BET specific surface area- The BET specific surface area of ​​the specific cellulose structure in the resin composition according to this embodiment is 0.1 m². 2 / g or more 200m 2 Preferably less than / g, 10m 2 / g or more 180m 2 Less than / g is more preferable, 30m 2 / g or more 160m 2 A value of less than / g is even more preferable. When the BET specific surface area of ​​a particular cellulose structure is above the lower limit mentioned above, the contact area between the particular cellulose structure and the biodegradable resin increases. As a result, the biodegradable resin becomes more easily biodegraded, and the function of the cellulose structure as a crystal nucleating agent is more easily exerted. This is presumed to improve the low-temperature biodegradability and heat resistance of the resin molded product. When the BET specific surface area of ​​a particular cellulose structure is below the above upper limit, aggregation of the particular cellulose structure is suppressed, and it is easier for it to disperse in a nearly uniform state within the biodegradable resin. As a result, the biodegradable resin becomes easier to biodegrade, and the function of the cellulose structure as a crystal nucleating agent is more easily exerted. This is presumed to improve the low-temperature biodegradability and heat resistance of the resin molded product.

[0047] The BET specific surface area of ​​cellulose structures in a resin composition is measured, for example, by separating the cellulose structures from the resin composition. Specifically, the resin composition is polished, and the cellulose structures are separated by specific gravity separation of the polishing powder. The BET specific surface area of ​​the separated cellulose structures is then measured using the method described later.

[0048] -Average diameter of specific cellulose structures in biodegradable resins- The specific cellulose structure is preferably present in the biodegradable resin with an average diameter of 0.001 μm to 50 μm, more preferably with an average diameter of 0.1 μm to 30 μm, and even more preferably with an average diameter greater than 1 μm and 15 μm or less. Hereafter, the average diameter of the cellulose structures present in the biodegradable resin will also be referred to as the "dispersion diameter." When the dispersion diameter of the specific cellulose structure is below the lower limit, the specific cellulose structure and the biodegradable resin are in a state close to miscibility. Conversely, when the dispersion diameter of the specific cellulose structure is above the lower limit, the specific cellulose structure and the biodegradable resin are separated. Therefore, the biodegradation of the specific cellulose structure is more likely to occur first, and its function as a crystal nucleating agent is more likely to be exhibited. As a result, it is presumed that the low-temperature biodegradability and heat resistance of the resin molded product will be improved. Furthermore, if the dispersion diameter of the specific cellulose structure is below the above upper limit, the contact area between the specific cellulose structure and the biodegradable resin increases. As a result, the biodegradable resin becomes more easily biodegraded, and the function of the cellulose structure as a crystal nucleating agent is more easily exerted. This is presumed to improve the low-temperature biodegradability and heat resistance of the resin molded product. Methods for controlling the dispersion diameter of specific cellulose structures within the aforementioned range include, for example, controlling it by kneading conditions such as kneading temperature and screw rotation speed in the melt kneading method described later, and controlling it by the average diameter, BET specific surface area, porosity, specific gravity, etc., of the specific cellulose structures.

[0049] The dispersion diameter of cellulose structures in biodegradable resins is measured as follows: The resin composition is cut. The cellulose structure on the cut surface of the resin composition is observed at a magnification of 1000x using a scanning microscope (SEM) to obtain an SEM image. The SEM image is imported into the image processing software "ImageJ," and the equivalent circle diameter is determined from the area of ​​the cellulose structure. Then, the average value of the equivalent circle diameters of 20 cellulose structures is calculated and used as the variance diameter.

[0050] (Method for manufacturing specific cellulose structures) The specific cellulose structure according to this embodiment can be obtained, for example, by the following method. (1) The raw cellulose derivative is added to a suitable solvent for the raw cellulose derivative, and then heated to obtain solution A in which the raw cellulose derivative is dissolved in the suitable solvent. (2) Add a poor solvent for the raw cellulose derivative to solution A to obtain solution B. (3) Solution B is rapidly cooled, and a gel-like substance (C) containing the raw cellulose derivative is produced by phase separation. (4) After washing the gel-like substance (C), saponification with alkali is performed. This yields a gel-like substance (D) containing a specific cellulose derivative with an adjusted degree of substitution. (5) After washing the gel-like substance (D), it is dried, and if necessary, coarse particles and aggregates are removed by crushing and sieving. This yields a specific cellulose structure, which is a porous structure mainly composed of a specific cellulose derivative. The crushing method is not particularly limited, but can be carried out using a dry grinding device such as a jet mill, vibratory mill, ball mill, or pin mill. The sieving method can be carried out using a known device such as a vibratory screen or wind screen.

[0051] Here, the degree of substitution of the specific cellulose derivative is controlled by the degree of saponification of the gel-like substance (C). Specifically, for example, when saponification is performed by alkaline treatment, the degree of substitution of the specific cellulose derivative is controlled by adjusting the alkaline treatment time. In this way, a specific cellulose structure is obtained, which is a porous structure mainly composed of a specific cellulose derivative whose degree of substitution is controlled to be between 0.2 and less than 1.7.

[0052] Furthermore, to obtain specific cellulose structures that are non-porous structures, there are methods such as obtaining cellulose derivative particles by suspension emulsification, or crushing cellulose acetate (DAC) raw materials.

[0053] (Content of specific cellulose structures) The content of the specific cellulose structure is preferably 0.1% to 20% by mass relative to the biodegradable resin, more preferably 0.1% to 10% by mass, and even more preferably 1% to 5% by mass. When the content of specific cellulose structures is within the above range, it becomes easier to obtain resin molded articles with sufficiently high low-temperature biodegradability and heat resistance.

[0054] <Other ingredients> This composition may contain other ingredients. Other components include, for example, plasticizers, flame retardants, compatibilizers, mold release agents, lightfastness agents, weathering agents, colorants, pigments, modifiers, drip inhibitors, antistatic agents, hydrolysis inhibitors, fillers, reinforcing agents (glass fiber, carbon fiber, talc, clay, mica, glass flakes, milled glass, glass beads, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, etc.), acid acceptors (oxides such as magnesium oxide and aluminum oxide; metal hydroxides such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, hydrotalcite, etc.; calcium carbonate; talc; etc.), and reactive trapping agents (e.g., epoxy compounds, acid anhydride compounds, carbodiimide, etc.). The content of other components is preferably 0% by mass or more and 5% by mass or less, based on the total amount of the resin composition. Here, "0% by mass" means that no other components are present.

[0055] <Properties of resin compositions> (crystallization heat) In this composition, the heat of crystallization is preferably 32 J / g or more and 45 J / g or less, more preferably 34 J / g or more and 40 J / g or less, and even more preferably 36 J / g or more and 40 J / g or less. By keeping the crystallization heat within the above range, it is possible to achieve both low-temperature biodegradability and heat resistance in the resin molded product. Specifically, if the crystallization heat is above the lower limit, the amount of crystallization in the resin molded product is large, making it easier to obtain heat resistance in the resin molded product. On the other hand, if the crystallization heat is below the upper limit, the decrease in low-temperature biodegradability caused by excessive crystallization in the resin molded product is suppressed. The heat of crystallization of a resin composition is determined by measuring its non-isothermal crystallization behavior using a differential scanning calorimeter (DSC6200, Seiko Instruments). Specifically, the heat of crystallization is determined from the area of ​​the exothermic peak that appears when the mixture is heated to 220°C, maintained for 5 minutes, and then cooled to 60°C at a rate of 1°C / min. The heat required for crystallization of a resin composition can be controlled, for example, by adjusting the kneading conditions when the resin composition is manufactured by melt kneading. Examples of such kneading conditions include kneading torque, kneading temperature, and screw rotation speed.

[0056] (Temperature Deflection (HDT)) In this composition, the heat deflection temperature (HDT) is preferably 125°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. However, from the viewpoint of moldability, the heat deflection temperature (HDT) is, for example, 200°C or lower. When the heat deflection temperature (HDT) is within the above range, a resin molded product with sufficiently high heat resistance can be obtained.

[0057] (Low temperature biodegradation rate) In this composition, the low-temperature biodegradation rate is preferably 5% or more, more preferably 10% or more, and even more preferably 20% or more, over 28 days. However, from the viewpoint of shape retention, the low-temperature biodegradation rate is, for example, 100% or less. The above low-temperature biodegradation rate is a value measured by a method conforming to ISO 14855-1:2012, except that the temperature condition is set to 25℃±2℃. If the low-temperature biodegradation rate falls within the above range, it becomes easier to obtain resin molded products that are sufficiently biodegradable even at 25°C.

[0058] Here, the temperature of deflection under load (HDT) and the low-temperature biodegradation rate are values ​​measured by the method described in the "Examples" section below.

[0059] <Method for producing resin compositions> Methods for producing this composition include, for example, mixing each component and then melt-kneading them. The means for melt-kneading are not particularly limited and include, for example, a twin-screw extruder, a Henschel mixer, a Banbury mixer, a single-screw extruder, a multi-screw extruder, a cone mixer, etc. Furthermore, by controlling the kneading conditions, a resin composition containing a specific cellulose structure and a biodegradable resin can be obtained by kneading the specific cellulose structure with the biodegradable resin.

[0060] Here, the average diameter of the specific cellulose structure used in the production of this composition may be 1 μm or more and 500 μm or less, 1 μm or more and 355 μm or less, or 1 μm or more and 150 μm or less. The method for measuring the average diameter of cellulose structures is as follows: A scanning microscope (SEM) is used to observe the cellulose structure at a magnification of 250x and obtain SEM images. The SEM images are imported into the image processing software "ImageJ," and the equivalent diameter of the cellulose structure is determined from its area. Then, the average of the equivalent diameters of 20 cellulose structures is calculated and used as the average diameter.

[0061] -BET specific surface area- The BET specific surface area of ​​the specific cellulose structure used in the production of this composition is 0.1 m². 2 / g or more 100m 2 Preferably less than / g, 10m 2 / g or more 90m 2 Less than / g is more preferable, 30m 2 / g or more 80m 2 A value of less than / g is even more preferable. When the BET specific surface area of ​​a particular cellulose structure is above the lower limit mentioned above, the contact area between the particular cellulose structure and the biodegradable resin increases. As a result, the biodegradable resin becomes more easily biodegraded, and the function of the cellulose structure as a crystal nucleating agent is more easily exerted. This is presumed to improve the low-temperature biodegradability and heat resistance of the resin molded product. When the BET specific surface area of ​​a particular cellulose structure is below the above upper limit, aggregation of the particular cellulose structure is suppressed, and it is easier for it to disperse in a nearly uniform state within the biodegradable resin. As a result, the biodegradable resin becomes easier to biodegrade, and the function of the cellulose structure as a crystal nucleating agent is more easily exerted. This is presumed to improve the low-temperature biodegradability and heat resistance of the resin molded product.

[0062] A method for obtaining a specific cellulose structure having a BET specific surface area within the aforementioned range includes, for example, a method of controlling the ratio of a good solvent to a poor solvent in the aforementioned method for producing the specific cellulose structure. By the above method, a cellulose structure is obtained in which the degree of substitution of the cellulose derivative contained as the main component is within the above range, and the BET specific surface area is within the above range.

[0063] The BET specific surface area of ​​the cellulose structure was measured using a multi-point automated measurement method with a specific surface area / pore distribution analyzer (BELSORP MAXII, Microtrac-Bel). The measurement temperature was 77K, and nitrogen gas was used as the adsorption gas. However, before measurement, the sample (i.e., the cellulose structure) is pre-treated by vacuum drying at 100°C for 24 hours to remove water and other substances adsorbed within the pores of the sample.

[0064] <Resin molded product> The resin molded article according to this embodiment contains the present composition. In other words, the resin molded article according to this embodiment is composed of the same composition as the present composition.

[0065] In this embodiment, injection molding is a method for molding resin molded articles, from the viewpoint of high freedom in shape. In other words, the resin molded article is an injection-molded article obtained by injection molding. The injection molding of the resin molded article according to this embodiment may be performed using commercially available equipment such as the NEX500, NEX150, NEX7000, PNX40, or SE50D manufactured by Nissei Plastic Industrial Co., Ltd.

[0066] The resin molded article according to this embodiment may be a resin molded article obtained by other molding methods. Other molding methods that may be applied include, for example, extrusion molding, blow molding, hot press molding, calendering, coating molding, casting, dipping molding, vacuum forming, and transfer molding.

[0067] Applications of the resin molded articles according to this embodiment include: housings for electronic and electrical equipment or home appliances; various parts for electronic and electrical equipment or home appliances; interior parts for automobiles; building block toys; plastic model kits; storage cases for CD-ROMs or DVDs; tableware; beverage bottles; food trays; wrapping material; film; sheets; and the like. [Examples]

[0068] Examples are described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" all refer to mass. Furthermore, unless otherwise specified, the following operations were carried out at room temperature of 25°C and atmospheric pressure.

[0069] [Example 1] <Fabrication of Cellulose Structures> As the cellulose acylate (1) below, cellulose diacetate (CA, Eastman Chemical Corporation, trade name: CA 398-30, number average molecular weight: 30,000) was used. A solution containing 10 parts by mass of cellulose acylate (1) and 33 parts by mass of dimethyl sulfoxide was placed in a container, and the solution was stirred at 90°C for 1 hour. After dissolving cellulose acylate (1) in dimethyl sulfoxide, 7 parts by mass of water was slowly added to the solution while stirring, and the mixture was stirred for another hour. The solution was then rapidly cooled by immersing the container in ice water to obtain a porous gel product by phase separation. The resulting gel was washed with 200 parts by mass of ethanol. The washed gel was immersed in a 1M sodium hydroxide aqueous solution for 30 minutes, and then washed with 200 parts by mass of water. The washed gel was dried to obtain a porous structure made of cellulose derivative (1). Subsequently, the obtained porous structure was crushed using a mill mixer and sieved using a 106 μm sieve to obtain a cellulose structure (1) in which the porous structure made of cellulose derivative (1) was finely ground.

[0070] <Preparation of resin composition> Polylactic acid (PLA, manufactured by NatureWorks, Ingeo3001D) was used as the biodegradable resin (1) below. One part by mass of the obtained cellulose structure (1) and 100 parts by mass of biodegradable resin (1) were fed from a hopper into a twin-screw extruder (Toshiba Machine Co., Ltd., TEM58SS). The cellulose structure and the biodegradable resin were kneaded, the discharged strand was cooled in a quench pool, and pelletized in a pelletizer to obtain a pelletized resin composition (1). The cylinder temperature during mixing was set to 200°C, and the mixing torque to 2600 N·m.

[0071] <Fabrication of resin molded products> The obtained resin composition (1) was dried at 70°C for 4 hours and loaded into an injection molding machine (Nissei Plastic Industrial Co., Ltd., NEX500). Then, a dumbbell test specimen (test section width 8 mm x thickness 4 mm x length 110 mm), as recommended by ISO 527, was molded to obtain a resin molded body (1). The dumbbell test specimen, which was the resin molded body (1), was annealed and crystallized as needed. The cylinder temperature during molding was set to 180°C, the mold temperature to 40°C, and the holding time in the mold to 2 minutes.

[0072] <Measurement and Evaluation> (Degree of substitution of cellulose derivatives) The degree of substitution of cellulose derivative (1) was measured using the method described above. The results are shown in Table 1 ("Degree of Substitution" in the table).

[0073] (Cellularization heat of resin composition) The non-isothermal crystallization behavior of a pelletized resin composition (1) was measured using a differential scanning calorimeter (DSC6200, Seiko Instruments). Specifically, the heat of crystallization was determined from the area of ​​the exothermic peak that appeared when the temperature was raised to 220°C and maintained for 5 minutes, and then cooled to 60°C at a rate of 1°C / min. The results are shown in Table 1 ("Heat" in the table).

[0074] (Dispersion diameter of cellulose structures) The dispersion diameter of the cellulose structure (1) in the resin composition (1) was measured by the method described above. The results are shown in Table 1 ("Dispersion Diameter" in the table).

[0075] (Number average molecular weight of cellulose derivatives) The number-average molecular weight of cellulose derivative (1) was measured using the method described above. The results are shown in Table 1 ("Molecular Weight" in the table).

[0076] (BET specific surface area of ​​cellulose structure) The BET specific surface area of ​​the cellulose structure (1) was measured using the method described above. The results are shown in Table 1 ("Specific Surface Area" in the table).

[0077] (Low-temperature biodegradation rate of resin molded products) The obtained resin molded body (1) was crushed using a lab mill (Dalton, LM-05), then sieved through a 100 μm mesh, and the resulting material was collected. Aerobic biodegradation was measured on the collected material using a method conforming to ISO 14855-1:2012, except that the temperature was set to 25°C ± 2°C, and the biodegradation rate after 28 days was determined. A higher biodegradation rate indicates better low-temperature biodegradability of the resin molded body. The results are shown in Table 1 ("Low-Temperature Biodegradation" in the table).

[0078] (Heat deflection temperature (HDT) of a molded resin body) The heat deflection temperature (HDT) at a load of 0.45 MPa was measured on the obtained resin molded body (1) using an HDT measuring device (Toyo Seiki Seisakusho, HDT-3) in accordance with ISO 75-1:2020. A higher HDT indicates better heat resistance of the resin molded body. The results are shown in Table 1 (indicated as "HDT" in the table).

[0079] [Examples 2-4] Cellulose structures (2) to (4) were obtained in the same manner as cellulose structure (1), except for the following changes. The immersion time of the gel in the 1M sodium hydroxide solution was changed from 30 minutes to 60 minutes, 15 minutes, and 120 minutes, respectively. Resin compositions (2) to (4) of Examples 2 to 4 were obtained in the same manner as resin composition (1), except for the following changes. Cellulose structures (2) to (4) were used instead of cellulose structure (1). Resin molded bodies (2) to (4) were obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin compositions (2) to (4) were used, respectively. Measurements and evaluations were performed for Examples 2-4 in the same manner as in Example 1. The results are shown in Table 1.

[0080] [Example 5] Cellulose structure (5) was obtained in the same manner as cellulose structure (1), except for the following changes. The concentration of the sodium hydroxide solution in which the gel was immersed was changed from 1M to 0.5M. Resin composition (5) of Example 5 was obtained in the same manner as resin composition (1), except that the following changes were made. Cellulose structure (5) was used instead of cellulose structure (1). A resin molded body (5) was obtained in the same manner as resin molded body (1), except for the following changes. • Resin composition (5) was used instead of resin composition (1). For Example 5, measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0081] [Comparative Examples 1-2] Cellulose structures (C1) to (C2) were obtained in the same manner as cellulose structure (1), except for the following changes. The immersion time of the gel in the 1M sodium hydroxide solution was changed from 30 minutes to 180 minutes and 10 minutes, respectively. Resin compositions (C1) to (C2) of Comparative Examples 1 and 2 were obtained in the same manner as resin composition (1), except for the following changes. Cellulose structures (C1) to (C2) were used instead of cellulose structure (1). Resin molded bodies (C1) to (C2) were obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin compositions (C1) to (C2) were used, respectively. Comparative Examples 1 and 2 were measured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0082] [Examples 6-9] Cellulose structures (6) to (9) were obtained in the same manner as cellulose structure (1), except for the following changes. The mixing torque was changed from 2600 N·m to 2400 N·m, 2800 N·m, 2500 N·m, and 3000 N·m, respectively. Resin compositions (6) to (9) of Examples 6 to 9 were obtained in the same manner as resin composition (1), except for the following changes. Cellulose structures (6) to (9) were used instead of cellulose structure (1). Resin molded articles (6) to (9) were obtained in the same manner as resin molded article (1), except for the following changes. Instead of resin composition (1), resin compositions (6) to (9) were used, respectively. For Examples 6 to 9, measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0083] [Examples 10-13] Cellulose structures (10) to (13) were obtained in the same manner as cellulose structure (1), except for the following changes. The cylinder temperature during mixing was changed from 200°C to 210°C, 190°C, 220°C, and 180°C, respectively. Resin compositions (10) to (13) of Examples 10 to 13 were obtained in the same manner as resin composition (1), except that the following changes were made. Cellulose structures (10) to (13) were used instead of cellulose structure (1). Resin molded bodies (10) to (13) were obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin compositions (10) to (13) were used, respectively. For Examples 10 to 13, measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0084] [Examples 14-17] Cellulose structures (14) to (17) were obtained in the same manner as cellulose structure (1), except for the following changes. Instead of cellulose acylate (1), the following cellulose acylates (2) to (5) were used. Cellulose acylate (2): Cellulose diacetate (number average molecular weight: 15000) Cellulose acylate (3): Cellulose diacetate (number average molecular weight: 50,000) Cellulose acylate (4): Cellulose diacetate (number average molecular weight: 10000) Cellulose acylate (5): Cellulose diacetate (number average molecular weight: 80,000) Resin compositions (14) to (17) of Examples 14 to 17 were obtained in the same manner as resin composition (1), except that the following changes were made. Cellulose structures (14) to (17) were used instead of cellulose structure (1). Resin molded bodies (14) to (17) were obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin compositions (14) to (17) were used, respectively. For Examples 14 to 17, measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0085] [Examples 18-21] Cellulose structures (18) to (21) were obtained in the same manner as cellulose structure (1), except for the following changes. The amount of dimethyl sulfoxide added to 10 parts by mass of cellulose diacetate was changed from 33 parts by mass to 66 parts by mass, 20 parts by mass, 70 parts by mass, and 18 parts by mass, respectively. Resin compositions (18) to (21) of Examples 18 to 21 were obtained in the same manner as resin composition (1), except that the following changes were made. Cellulose structures (18) to (21) were used instead of cellulose structure (1). Resin molded bodies (18) to (21) were obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin compositions (18) to (21) were used, respectively. For Examples 18-21, measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0086] [Examples 22-24] The same cellulose structure (1) was used as cellulose structures (22) to (24), respectively.

[0087] Resin compositions (22) to (24) of Examples 22 to 24 were obtained in the same manner as resin composition (1), except that the following changes were made. Cellulose structures (22) to (24) were used instead of cellulose structure (1). Instead of biodegradable resin (1), the following biodegradable resins (2) to (4) were used. Biodegradable resin (2): Polybutylene succinate (PBS, Bio-PBS manufactured by PTT MCC Biochem) Biodegradable resin (3): Polybutylene adipate / terephthalate copolymer resin (PBAT, BASF Ecoflex) Biodegradable resin (4): Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH, manufactured by Kaneka, GREEN PLANET) The cylinder temperatures were changed from 200°C to 170°C, 170°C, and 160°C, respectively. The mixing torque was changed from 2600 N·m to 1500 N·m, 1600 N·m, and 1300 N·m, respectively.

[0088] Resin molded bodies (22) to (24) were obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin compositions (22) to (24) were used, respectively. The cylinder temperatures were changed from 180°C to 170°C, 160°C, and 140°C, respectively. The mold temperatures were changed from 40°C to 30°C, 30°C, and 30°C, respectively. The holding time within the mold was changed from 2 minutes to 4 minutes, 4 minutes, and 6 minutes, respectively. For Examples 22-24, measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0089] [Comparative Example 3] A resin composition (C3) for Comparative Example 3 was obtained in the same manner as resin composition (1), except that the following changes were made. • Cellulose structure (1) was not used. Resin molded body (C3) was obtained in the same manner as resin molded body (1), except for the following changes. Resin composition (C3) was used instead of resin composition (1). Comparative Example 3 was measured and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0090] [Comparative Example 4] A resin composition (C4) for Comparative Example 4 was obtained in the same manner as resin composition (1), except that the following changes were made. Instead of the cellulose structure (1), cellulose nanofiber (CN, manufactured by Chuetsu Pulp & Paper Co., Ltd., product name: Nano Forest) was used. Resin molded body (C4) was obtained in the same manner as resin molded body (1), except for the following changes. Resin composition (C4) was used instead of resin composition (1). Comparative Example 4 was measured and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0091] [Comparative Example 5] A resin composition (C5) for Comparative Example 5 was obtained in the same manner as resin composition (1), except that the following changes were made. Instead of the cellulose structure (1), zinc phenylphosphonate (ZP, manufactured by Nissan Chemical Corporation, trade name: EcoPromote) was used. Resin molded body (C5) was obtained in the same manner as resin molded body (1), except for the following changes. Instead of resin composition (1), resin composition (C5) was used. Comparative Example 5 was measured and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0092] [Table 1]

[0093] [Table 2]

[0094] From the above results, it can be seen that in this example, a resin molded article with a higher low-temperature biodegradation rate and heat deflection temperature (HDT) is obtained compared to the comparative example. In other words, in this example, a resin molded article with better biodegradability and heat resistance at 25°C is obtained compared to the comparative example.

[0095] (Note) This embodiment includes the following aspects. (((1))) Biodegradable resin and A cellulose structure containing a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.7 as the main component, A resin composition containing the following: (((2))) The resin composition according to (((1))), wherein the cellulose structure is present in the biodegradable resin with an average diameter of 0.001 μm or more and 50 μm or less. (((3))) The resin composition according to (((1))) or (((2))), wherein the number average molecular weight of the cellulose derivative is 15,000 or more and 50,000 or less. (((4))) The resin composition according to any one of (((1))) to (((3))), wherein the heat of crystallization of the resin composition is 32 J / g or more and 45 J / g or less. (((5))) The resin composition according to any one of (((1))) to (((4))), wherein the biodegradable resin is at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate. (((6))) A method for producing a resin composition, comprising mixing a biodegradable resin with a cellulose structure mainly composed of a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.7. (((7))) The BET specific surface area of ​​the cellulose structure is 0.1 m². 2 / g or more 100m 2 A method for producing the resin composition described in (((6))) such that the amount is less than or equal to / g. (((8))) A method for producing the resin composition according to (((6))) or (((7))), wherein the number average molecular weight of the cellulose derivative is 15,000 or more and 50,000 or less. (((9))) A method for producing the resin composition according to any one of (((6))) to (((8))), wherein the heat of crystallization of the resin composition is 32 J / g or more and 45 J / g or less. (((10))) The method for producing the resin composition according to any one of (((6))) to (((9))), wherein the biodegradable resin is at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate.

[0096] According to the invention of (((1))) or (((5))), a resin composition is provided that yields a resin molded article with good biodegradability and heat resistance at 25°C compared to cases where the degree of substitution of the cellulose derivative is less than 0.2 or 1.7 or more, in a resin composition comprising a biodegradable resin and a cellulose structure mainly composed of a cellulose derivative. According to the invention of (((2))), a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the average diameter of the cellulose structures present in the biodegradable resin is less than 0.001 μm or greater than 50 μm. According to the invention of (((3))), a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the number average molecular weight of the cellulose derivative is less than 15,000 or more than 50,000. According to the invention of (((4))), a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the crystallization heat of the resin composition is less than 32 J / g or more than 45 J / g. According to the invention of (((6))) or (((10))), a method for producing a resin composition is provided, which includes mixing a biodegradable resin with a cellulose structure mainly composed of a cellulose derivative, and provides a resin molded article that has better biodegradability and heat resistance at 25°C compared to cases where the degree of substitution of the cellulose derivative is less than 0.2 or 1.7 or more. According to the invention of (((7))), the BET specific surface area of ​​the cellulose structure is 0.1 m². 2 Less than / g or 100m 2 A method for producing a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the value exceeds / g. According to the invention of ((8)), a method for producing a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the number average molecular weight of the cellulose derivative is less than 15,000 or more than 50,000. According to the invention of (((9))), a method for producing a resin composition is provided that yields a resin molded article with better biodegradability and heat resistance at 25°C compared to cases where the crystallization heat of the resin composition is less than 32 J / g or more than 45 J / g.

Claims

1. Biodegradable resin and A cellulose structure containing a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.7 as the main component, A resin composition containing the following:

2. The resin composition according to claim 1, wherein the cellulose structure is present in the biodegradable resin with an average diameter of 0.001 μm or more and 50 μm or less.

3. The resin composition according to claim 1 or claim 2, wherein the number average molecular weight of the cellulose derivative is 15,000 or more and 50,000 or less.

4. The resin composition according to claim 1 or claim 2, wherein the heat of crystallization of the resin composition is 32 J / g or more and 45 J / g or less.

5. The resin composition according to claim 1 or claim 2, wherein the biodegradable resin is at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate.

6. A method for producing a resin composition, comprising mixing a biodegradable resin with a cellulose structure mainly composed of a cellulose derivative having a degree of substitution of 0.2 or more and less than 1.

7.

7. The BET specific surface area of ​​the cellulose structure is 0.1 m². ２ / g or more 100m ２ A method for producing the resin composition according to claim 6, wherein the amount is less than or equal to / g.

8. A method for producing the resin composition according to claim 6 or claim 7, wherein the number-average molecular weight of the cellulose derivative is 15,000 or more and 50,000 or less.

9. The method for producing the resin composition according to claim 6 or claim 7, wherein the heat of crystallization of the resin composition is 32 J / g or more and 45 J / g or less.

10. The method for producing the resin composition according to claim 6 or claim 7, wherein the biodegradable resin is at least one selected from the group consisting of polylactic acid, polybutylene adipate / terephthalate copolymer resin, polyalkylene succinate, polyalkylene succinate adipate, and polyhydroxyalkanoate.

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